We were there in Jan and got free refills at
1)Belle Vue room (in the morning)
2)That Coffee cart on the board walk (can't remember what its called - but it was open in the evening)
3)The boardwalk bakery,
4)the pizza window on the boardwalk.
5) pool bar (almost forgot that one)
The only thing was that because the boardwalk has no area to get the drinks yourself, they would always give is our drinks in a regular cup, which was fine with us because we could throw it out and not worrie about cleaning out refillable mugs.
I think a lot of people don't like that there is no "station" to get your own refills, but we didn't mind it at all..